It is common practice to form a neck in a container body such as a beverage can by a “die necking” process. In a die necking process, cans are pushed longitudinally into dies so as gradually, over several necking stages, to reduce the neck diameter. The infeed to such a process may include a conveyor carrying a row of can bodies, in which the can bodies contact each other. In the conveyor, the can bodies have a “pitch” (i.e. the distance between their centres) of one can diameter. The can bodies are fed from this conveyor to an infeed turret of the processing (in this example, die necking) machine.
WO 2010/026115 A describes a triple turret infeed and waxer assembly comprising an infeed turret and a waxer turret with a transfer turret between the infeed and waxer turrets. The infeed assembly of this application includes an infeed turret which receives incoming can bodies from a chute, an infeed transfer turret and a waxer turret. The number of pockets on the turrets is the same, thereby avoiding damage when waxing rollers on the waxing turret engage an incoming can body. Whilst the invention of this application teaches how to break up the acceleration of the can bodies, there are no distinct tool groups to which the waxed cans are fed.
EP 1828035 A (CROWN PACKAGING TECHNOLOGY, INC) describes container processing equipment comprising multi-stage process handling equipment of about 50 individual stages, each stage requiring different tooling or “tool groups”. The process handling equipment comprises apparatus with at least one rotatable process turret having a number of pockets, each pocket being adapted to support an article. The pockets are divided into groups, with each group of pockets having associated tooling. Although the apparatus also includes a re-phase means to transfer an article from one group of pockets to the next, the pitch of a can is not changed. Instead, the multi-stage process is a system for moving the can one pitch so that the can is presented, say, to the second members of the tool groups on the second recirculation, or third members of the tool groups on the third recirculation (or nth members of the tool groups on the nth recirculation).
The challenge for a rotary machine infeed system for feeding cans to any container manufacturing process including die necking, is that the machine takes delivery of container bodies which are spaced or “pitched” in a linear fashion, and the infeed system must change the pitch between the container bodies to that of a circular turret—and a larger pitch. The processing pitch may also need to be larger in order to accommodate tools for performing the necking process. The manufacturing process will also have to be carried out at the line speed, often in excess of 1500 containers per minute or greater.
Each turret on a rotary machine has a number of pockets, each pocket being adapted to receive and retain a containers such as a can body, for example by vacuum. The pockets to carry the can bodies on each circular turret are each separated by a (pocket) pitch. The closer this pocket pitch is to the can body diameter the better the feed onto the infeed turret.
The present invention seeks to provide an infeed apparatus comprising a series of turrets, which has the facility to change the rotational speed of individual turrets, the turrets having fixed centre distances (between their rotating turret axes) and differing numbers of pockets, so as to be able to deliver cans at discrete circular pitches to a container manufacturing machine.